London -LRB- CNN -RRB- -- South African double-amputee sprinter Oscar Pistorius , who made headlines at the Olympics , set a world record on Saturday in London in defense of the first of his three Paralympic titles .

On day three of the Games , he ran 21.30 in men 's 200m-T44 title in the first round Saturday evening , easily besting other racers in his heat . The paralympic movement classifies events , using terms like T44 , to group competitors based on their disability .

His biggest threats in Sunday 's gold-medal final will include Brazilian Alan Fonteles Cardoso Oliveira , American sprinter Blake Leeper and South Africa 's Arnu Fourie , based on their qualifying times .

Pistorius , who uses carbon fiber prosthetic blades , made it to the semifinals of the individual 400-meter and the 400-meter relay final at the Olympics last month , running against able-bodied athletes .

In the Paralympics , which are the also being held in London , Pistorius is also competing in the men 's 100-meter-T44 -LRB- set for next Wednesday and Thursday -RRB- and the 400-meter-T44 -LRB- happening Friday and Saturday -RRB- , both of which he won in Beijing four years ago . He 's also part of South Africa 's 4 X 100-meter T42/T46 relay team , which is scheduled to race Wednesday .

The thin line : Paralympic classification

Competition was intense Saturday in Paralympic competitions in and around Great Britain 's capital , with 49 gold medals on the line across seven sports , including athletics , track cycling , swimming and equestrian .

Britain 's Richard Whitehead sprinted to victory earlier Saturday in the men 's 200m - T42 , setting a new world record in the process and shedding tears of joy at the finish . Team USA 's Shaquille Vance took the silver medal .

There was also drama in the velodrome Saturday .

Britain 's Neil Fachie , piloted by Barney Storey , smashed the world record to earn gold in the men 's individual B 1-kilometer time trial , an event on a tandem bicycle for the visually impaired .

There was bitter disappointment , though , for the cyclist whose record he took . World champion and fellow Briton Anthony Kappes , piloted by Craig Maclean , had his medal hopes dashed after the chain on their bike failed twice .

Britain 's Sarah Storey , wife of Barney Storey , made it a double gold for the household Saturday with victory in the women 's individual C4-5 500-meter time trial , while U.S. cyclist Jennifer Schuble took silver .

The win gave Sarah Storey , who was born without a functioning left hand , her second gold of the Games and an impressive 20 Paralympic medals in total across the swimming and cycling disciplines . She has also competed successfully against able-bodied athletes .

Gold medal in the men 's individual C4 cycling pursuit went to Carol-Eduard Novak from Romania , with silver for Jiri Jezek of the Czech Republic . Britain 's Jody Cundy took bronze , a day after he was disqualified for a false start in the time trial .

Australian world champion Michael Gallagher won the men 's individual C5 pursuit , holding Britain 's Jon-Allan Butterworth , a military veteran who lost an arm to a rocket attack in Iraq five years ago , to second place .

China 's Yin He set a world record in the women 's C1-2-3 500-meter time trial to take gold .

There is a tense wait ahead for Team USA 's 17-year-old Victoria Arlen , who earlier this week was ruled ineligible to swim at the Games by the International Paralympic Committee .

Arlen 's appeal against the ruling was upheld Thursday , meaning she could swim in Saturday 's 400-meter freestyle heats -- winning hers by a convincing 19-second margin -- but her classification is still subject to review by the IPC .

British medal hope Ellie Simmonds , also 17 , won her heat in a time a fraction faster than Arlen , the world record holder . That order held up in the finals , with Simmonds setting a world record in finishing a second ahead of Arlen -- with the two of them both 13 seconds faster than any other competitor .

Arlen 's classification problems came after fellow U.S. Paralympians Justin Zook and Mallory Weggeman were reclassified earlier this week . Arlen , from New Hampshire , was a talented able-bodied swimmer until a neurological disease left her paralyzed in both legs .

The complex system of disability classification , which ensures athletes compete against those who are similarly-abled , is considered an essential tool for the Paralympic movement .

On the track , the crowd gave a huge reception to Houssein Omar Hassan , who entered the Games on a wild card and is Djibouti 's first Paralympic runner . He finished nearly 7 minutes behind the next slowest competitor in the 1,500-meter race but was applauded for his spirit in finishing .

Over at Eton Manor , the first Paralympics-only venue to be built for the Games , the Netherlands ' wheelchair tennis star Esther Vergeer is looking to extend her decade-long dominance of the sport .

Vergeer -- who already has five Paralympic wheelchair tennis titles , three in singles , two in doubles -- beat Japan 's Kanako Domori in straight sets in the first round of the women 's singles . The rules for this competition are almost the same as for able-bodied tennis , but the ball is allowed to bounce twice .

In another display of dominance , Nigeria took its fifth powerlifting medal of the Games on Saturday , compliments of Esther Oyema in the women 's -48 kilograms competition .

CNN 's Tom McGowan contributed to this report .

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NEW : South Africa 's Oscar Pistorius sets a world record in a 200-meter semifinal heat

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Several Britons win Paralympic gold , including Richard Whitehead and Sarah Storey

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China 's Yin He sets a world record and wins gold in a cycling event

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The UK 's Ellie Simmonds edges out Team USA 's Victoria Arlen in 400-meter freestyle